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Tails of Seattle: A pets blog

Your local source for news and tips about dogs, cats and other critters, featuring fun videos, reader photos, Q&As and more.

April 15, 2011 at 10:45 AM

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Veterinary Q&A: When to spay or neuter

Posted by Neena Pellegrini

Dr. Harmon Rogers, the director of WSU's Veterinary Teaching Hospital in Pullman, is answering this week's question.

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Question: Can a cat or dog be spayed or neutered at too young an age? At what age should they be altered?:

Answer: The short answers are: 1) Yes, spaying or neutering can be done at too young an age; and 2) surgical altering should be done before a pet is involved in producing an unwanted litter.

Now, while this may seem equivocal or confusing, I urge the readers to press on.

First, deciding what to do for any specific pet may be difficult.

Early-age spaying and neutering came along in an attempt to reduce unwanted and ownerless cats and dogs.

Many puppies and kittens are taken from animal shelters between 2 and 4 months of age. If a pet is surgically altered when they are taken, then they won't later breed and add to the overpopulation problem.

For that reason spaying and neutering often is done as early as 8 weeks of age in kittens and puppies from shelters. If you think about what might happen to a future unwanted kitten or puppy, this makes a lot of sense.

The most immediate risk to the kitten or puppy undergoing an early-age spay or neuter is the risk from anesthesia and recovery from surgery. Basically, very small animals have a large body surface area in comparison with their body mass. This means they lose body heat more readily and can become hypothermic when they are anesthetized. That can lead to a slow recovery from surgery or even death.

Veterinarians routinely operating on very tiny patients are aware of this problem and take steps to mitigate it and keep the patient warm. However, the best way to avoid the risk of hypothermia and surgical death is hold off on doing surgery until the patient is more fully grown.

Next, let's consider what happens when spaying or neutering removes the normal reproductive hormones and what are the pros and cons of surgery at different ages.
For a long time the general opinion was spaying and neutering at the earliest age was always best. We know more now.

In general, reducing the reproductive drive of an animal diminishes roaming for mates, reducing the chance of being hit by a car and the chance of being injured in a fight with another animal. Lowering reproductive hormones decreases urine marking, decreases aggressiveness between animals, and sometimes, decreases aggressiveness with people. The earlier spaying or neutering is done, the earlier this will happen.

The spayed or neutered animal won't develop uterine cancer, ovarian cancer, and testicular cancer. Its risk of mammary cancer, uterine infection, and some forms of prostate disease are also decreased.

But, we've now learned that intact animals with normal reproductive hormones have decreased risks of some forms of cancer, such as blood, bone, prostate and bladder cancers. Intact animals have lower instances of urinary tract infections, diabetes mellitus, hypothyroidism and cruciate ligament injuries.

These are all very confounding. For some problems there is benefit from spaying and neutering at the earliest age possible. For others there is benefit from waiting and even not spaying or neutering.

For example, the benefits noted as far as cruciate ligament injuries go applies when the animal is growing. Once growth stops being intact doesn't matter.

The beneficial effect from spaying for prevention of mammary cancer declines as the patient ages, so the earlier a pet is spayed the better.

The beneficial effect from neutering for prostate disease is more important with the older dog. Prostate disease is very uncommon in young dogs.

So in the final analysis the proper time to spay or to neuter an animal depends on a lot of things. Spend some time with your veterinarian talking about your goals for your pet and your personal concerns. Then you'll know what should be done.

Dr. Harmon Rogers

Rogers is a clinicial associate professor at WSU and director of the Veterinary Teaching Hospital in Pullman. He graduated from Texas A&M's College of Veterinary Medicine in 1974.

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Do you have a question about pet health? Ask now! We'll pose some of your questions to a local vet in an upcoming post.

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